In recent years, to handle image information as digital information and achieve high-efficiency information transmission and accumulation, apparatuses compliant with a standard, such as MPEG for compressing image information through orthogonal transforms and motion compensations by using redundancy inherent to image information, have been spreading both among broadcast stations to distribute information and among general households to receive information.
Particularly, MPEG2 (ISO/IEC 13818-2) is defined as a general-purpose image encoding technique. The MPEG2 compression technique is applicable to interlaced images and non-interlaced images, and to standard-resolution images and high-definition images. Currently, MPEG2 is used for a wide range of applications for professionals and general consumers. By using the MPEG2 compression technique, a bit rate of 18 to 22 Mbps is assigned to interlaced images with a high resolution of 1920×1088 pixels, for example, to achieve high compression rates and excellent image quality.
MPEG2 is designed mainly for high-quality image encoding for broadcasting, but is not compatible with lower bit rates than MPEG1 or encoding techniques with higher compression rates. As mobile terminals are becoming popular, the demand for such encoding techniques is expected to increase in the future, and to meet the demand, the MPEG4 encoding technique has been set as a standard. As for image encoding techniques, the ISO/IEC 14496-2 standard was approved as an international standard in December 1998.
Further, in recent years, H.264 and MPEG-4 Part 10 (Advanced Video Coding, hereinafter referred to as H.264/AVC), which can achieve a higher encoding efficiency than encoding techniques such as MPEG2 and MPEG4, have become an international standard, though requiring a larger amount of calculation for decoding. H.264/AVC is based on H.26L, but also has functions unsupported by H.26L.
Patent Document 1 and the like disclose more efficient image data encoding using H.264/AVC.